[QGIS-Developer] Duplicate Features

[Matthias Kuhn]

Hi list,

For QGIS 3.0 we have created a new feature "duplicate features", that
allows duplicating features with associated children whenever a relation
is defined as "composition" (https://github.com/qgis/QGIS/pull/5448).

There is a new configuration option in place as well as core
functionality with unit tests.

However, this code is currently nowhere triggered inside QGIS. We have
written custom python code for a feature action to make it work for the
client who ordered this. Still, it is unfortunate to have a
configuration option which has no effect without writing custom python code.

We could add this code as default action, given that this is opt-in and
the underlying code is tested by unit tests I would feel comfortable to
bring this in at the current state and treat this as a GUI fix.

If others feel uncomfortable, please say so and we can point the users
towards the documentation and mention the python code for the action for
copy pasting there, or mark the configuration option as experimental.

Thanks
Matthias